This invention is related to refrigeration systems which can be powered from either two alternately available sources. More particularly this invention is related to refrigeration systems for engine powered vehicles and the like where the engine power is used to operate the refrigeration system in one mode of operation and a source of alternating current electrical power is used to operate the refrigeration system in a second mode of operation.
Prior to my auxiliary refrigeration power means described in the aforementioned related material there was no known way to operate a refrigeration system from two alternately usable power sources other than connecting a single compressor with the two power sources and using belts, clutches, and other mechanical apparatus to couple the power source with the single compressor. My prior invention provided a refrigeration system which is operable by either an alternating current power source through an alternating current motor and a compressor or through a second compressor which is connected with a direct current electrical motor. This device uses a rectifier in switching circuits to connect either the alternating current electric motor or the direct current electric motor to provide power for the refrigeration system either from a commonly available source of alternating current or from the battery of an engine powered vehicle. This apparatus requires specially produced direct current electric motors capable of reliably operating a compressor. Several devices are known in the refrigeration art for operating refrigeration systems from the engine of a motor vehicle by means of a compressor connected with the crank shaft of the vehicle's engine. However, these prior art devices are limited to extremely simple refrigeration systems having only the basic and necessary operating elements and they are specifically constructed for use in airconditioning automobiles, trucks, and the like wherein the temperature range of the refrigerated compartment which is the interior of the automobile is not particularly critical. There are no devices known in the prior art which will operate a refrigeration apparatus in a vehicle from either an alternating current power source or from the vehicle's engine and maintain a refrigerated compartment in the vehicle within a predetermined and certain temperature range without using separate refrigeration systems or the above-noted mechanical devices. Furthermore, no refrigeration systems are known in the art which will refrigerate multiple compartments of a vehicle at different temperature ranges and be powerable from either an alternating current power source or a single compressor on the vehicle's engine.